Abortion Surveillance -- United States, 1991

Problem/Condition: From 1980 through 1991, the number of legal
induced abortions reported to CDC remained stable, varying each
year by less than or equal to 5%.

Reporting Period Covered: This report summarizes and reviews
information reported to CDC regarding legal induced abortions
obtained in the United States during 1991.

Description of System: For each year since 1969, CDC has compiled
abortion data received from 52 reporting areas: 50 states, the
District of Columbia, and New York City.

Results: In 1991, 1,388,937 abortions were reported -- a 2.8%
decrease from 1990. The abortion ratio was 339 legal induced
abortions per 1,000 live births, and the abortion rate was 24 per
1,000 women 15-44 years of age. Women who were undergoing an
abortion were more likely to be young, white, and unmarried; most
had had no previous live births and had been obtaining an abortion
for the first time. More than half (52%) of all abortions were
performed at or before the 8th week of gestation, and 88% were
before the 13th week. Younger women (i.e., women less than 19 years
of age) were more likely to obtain abortions later in pregnancy
than were older women.

Interpretation: Since 1980, the number and rate of abortions have
remained relatively stable, with only small year-to-year
fluctuations of less than or equal to 5%. However, since 1987, the
abortion-to-live-birth ratio has declined; in 1991, the abortion
ratio was the lowest recorded since 1977. An increasing rate of
childbearing may partially account for this decline.

Actions Taken: An accurate assessment of the number and
characteristics of women who obtain abortions in the United States
is necessary both to monitor efforts to prevent unintended
pregnancy and to identify and reduce preventable causes of
morbidity and mortality associated with abortions.

INTRODUCTION

In 1969, CDC began abortion surveillance to document the
number and characteristics of women obtaining legal induced
abortions and to assist efforts to identify and reduce preventable
causes of morbidity and mortality associated with abortions. This
report is based on abortion data for 1991 provided to CDC's
National Center for Chronic Disease Prevention and Health
Promotion, Division of Reproductive Health.

METHODS

For 1991, CDC compiled data from 52 reporting areas: 50
states, the District of Columbia, and New York City. The total
number of legal induced abortions was available from all reporting
areas, and most of these areas provided information on the
characteristics of women who obtained abortions. For 47 reporting
areas, data were provided from the central health agency *; for the
other five areas, data were provided from hospitals and other
medical facilities. Abortions were reported by the state in which
they were performed.

Women who obtained legal induced abortions were grouped by
5-year age groups. Both ratios (i.e., the number of abortions per
1,000 live births) and rates (the number of abortions per 1,000
women) are presented by age group. Ratios were calculated by using
the number of live births provided by each state's central health
agency (except where noted), and rates were calculated by using the
number of women recorded in special unpublished tabulations
provided by the U.S. Bureau of the Census. Rates for women less
than 15 years of age were based on the number of women ages 10-14
years, and rates for women greater than or equal to 40 years of age
were based on the number of women ages 40-44 years.

Race was categorized by either three groups ({a} white {which
included Hispanics}, {b} black, and {c} all other races) or two
groups ({a} white {which included Hispanics} and {b} black and
other races). Other races included Asians/Pacific Islanders, Native
Americans, Alaskan Natives, and those classified as "other race."
In 1990, data regarding Hispanic ethnicity were first available on
abortion reports submitted by central health agencies to CDC. In
this report for 1991, Hispanic ethnicity was reported separately by
race.

Gestational age (in weeks) at the time of abortion was
reported by most states from estimates derived from the time
elapsed since the woman's last menstrual period. In six states,
gestational age was reported on the basis of the physician's
estimate, which could have included information from the clinical
examination and the time elapsed since the last menstrual period.

RESULTS

For 1991, 1,388,937 legal abortions were reported to CDC -- a
2.8% decrease from the number reported for 1990 (1) Table_1.
From
1970 through 1982, the reported number of legal abortions in the
United States increased every year Figure_1; the largest
percentage increase occurred from 1970 to 1972. From 1976 through
1982, the annual increase declined continuously and reached a low
of 0.2% for 1980-1981. From 1980 through 1991, the number of
abortions remained relatively stable; year-to-year fluctuations
were less than or equal to 5%.

The national abortion ratio increased from 1970 to 1980,
peaked at 364 per 1,000 live births in 1984, and began to decline
steadily after 1987 to 339 per 1,000 in 1991 (Figure_1;
Table_2.
The national abortion rate increased from 17 abortions per 1,000
women ages 15-44 years in 1974 to 25 per 1,000 in 1980 and has
since remained at a rate of 23-24 per 1,000.

In 1991, as in previous years, most abortions were performed
in California, New York City, and Texas; the fewest were performed
in North Dakota, South Dakota, West Virginia, and Wyoming (1,2)
Table_3. For women whose state of residence was known, about
92%
had obtained the abortion within their own state. The percentage of
abortions obtained by out-of-state residents ranged from
approximately 51%
in the District of Columbia to less than 1% in Hawaii. Ten
reporting areas
could not provide data concerning abortions obtained by
out-of-state
residents.

In 1991, 41 states, the District of Columbia, and New York
City reported legal abortions by age. Women ages 20-24 years
obtained 34% of all abortions; women ages less than 15 years
obtained less than 1% of all abortions Table_4. Abortion ratios
were highest for the youngest women (767 abortions per 1,000 live
births for women ages less than 15 years and 462 per 1,000 for
women ages 15-19 years) and the oldest women (469 per 1,000 for
women ages greater than or equal to 40 years); the ratio was lowest
for women ages 30-34 years (187 per 1,000 women) Figure_2.
Among
teenagers, the abortion ratio was highest for those who were less
than 15 years of age and lowest for those who were 19 years of age
Table_5. Abortion rates were highest for women ages 20-24 years
(42 per 1,000 women) and lowest for women at the reproductive-age
extremes (one abortion per 1,000 women ages less than 15 years and
two abortions per 1,000 women ages greater than or equal to 40
years) Table_4.

For most age groups, the abortion ratio rose between 1974 and
the early to mid-1980s and declined thereafter, particularly for
the youngest and oldest women of reproductive age Figure_3. The
abortion ratios for women ages less than 15 years and, since 1983,
those ages 15-19 years were higher than for the other age groups.
During 1991, abortion ratios decreased for the fourth consecutive
year for women less than 20 years of age. The abortion ratio for
women less than 15 years of age was the lowest recorded ratio for
the time period, and the ratio for women 15-19 years of age was the
lowest recorded since 1974. The abortion ratio for women 20-34
years of age (i.e., the group with the highest fertility rate)
remained relatively stable after 1974 (3).

During 1991, approximately 52% of reported legal abortions
were obtained at or before 8 weeks of gestation, and about 88% were
obtained before 13 weeks Table_6. Approximately 4% of abortions
were obtained at 16-20 weeks of gestation, and approximately 1%
were obtained at greater than or equal to 21 weeks.

Approximately 98% of legal abortions were performed by
curettage, and less than 1% by intrauterine saline or prostaglandin
instillation Table_7. Hysterectomy and hyster-otomy were used
rarely; less than 0.02% of abortions were performed by these
methods.

Thirty-four states, the District of Columbia, and New York
City reported the race of women who obtained legal abortions. As in
previous years, almost two thirds of women who obtained abortions
were white (1,2) Table_8. The abortion ratio for black women
(502
per 1,000 live births), however, was more than twice that for white
women (246 per 1,000 live births). The abortion ratio for women of
other races (300 per 1,000 live births) was 1.2 times greater than
that for white women. In addition, the abortion rate for black
women (41 per 1,000 black women) was 2.6 times greater than the
rate for white women (16 per 1,000 white women).

Twenty states, the District of Columbia, and New York City
reported data on legal abortions classified by Hispanic ethnicity
Table_9. The percentage of Hispanic women who obtained
abortions
in these reporting areas ranged from less than 1% in several states
to approximately 38% in New Mexico. For Hispanic women in these
reporting areas, the abortion ratio was 300 per 1,000 live births
--
slightly lower than the ratio for non-Hispanics in the same areas
(332 per 1,000 live births). However, the abortion rate per 1,000
Hispanic women (28 per 1,000 women) was slightly greater than the
rate per 1,000 non-Hispanic women (22 per 1,000 women).

Seventy-six percent of women who obtained abortions were
unmarried Table_10. The percentage varied by state, from 59% in
Utah to 82% in Kansas. The abortion ratio was more than nine times
greater for unmarried women than for married women (815 vs. 89
abortions per 1,000 live births).

Approximately 47% of women who obtained legal abortions had
had no previous live births, and about 89% had had two or fewer
previous live births Table_11. The abortion ratio was highest
for
women who had had no live births and lowest for women who had had
four or more live births.

About 55% of women had been obtaining an abortion for the
first time. Approximately 16% of women had had at least two
previous abortions Table_12.

The age distribution of women who obtained a legal abortion
differed only slightly by race Table_13. However, for women
less
than 15 years of age, the percentage who were black or of other
races, although small (1.3%), was more than twice the percentage
who were white (0.6%). The percentage of unmarried women who were
black or of other races (81%) was also slightly higher than the
percentage who were white (76%). Few differences were found by age
and Hispanic ethnicity Table_14, but among married women who
had
obtained an abortion, a greater percentage were Hispanic than
non-Hispanic.

Most women obtained an abortion during the first 12 weeks of
pregnancy; however, teenagers (i.e., women ages less than 19 years)
were more likely than older women to obtain abortions later in
pregnancy Table_15. The percentage of women who obtained an
abortion early in pregnancy (i.e., at less than or equal to 8 weeks
of gestation) increased with age, and the percentage who obtained
an abortion late in pregnancy (at greater than or equal to 16 weeks
of gestation) decreased with age Figure_4. Women who were black
or of other races were more likely to obtain an abortion later in
pregnancy than were white women Table_15. Although Hispanic
women
were more likely than non-Hispanic women to have had an abortion at
less than or equal to 8 weeks of gestation, the overall differences
between Hispanic and non-Hispanic women in the timing of abortions
were minimal.

More than 99% of abortions at less than or equal to 12 weeks
of gestation were performed by curettage (primarily suction
procedures) Table_16. After 12 weeks of gestation, the most
frequently used procedure was also curettage, although it was
usually reported as dilatation and evacuation (D&E). Most
intrauterine instillations involved the use of saline and were
performed at greater than or equal to 16 weeks of gestation.

DISCUSSION

Although the annual number of abortions remained relatively
stable, in 1991 the national abortion-to-live-birth ratio was the
lowest recorded since 1977. The abortion ratio increased steadily
from 1970 through 1980, decreased slightly during 1981-1983,
increased to its highest level in 1984, remained fairly stable
until 1987, and then began to decline Figure_1. Increased birth
rates for women of all ages might have contributed to this decline
(3). Other factors that could have affected the decline in the
abortion ratio include reduced access to abortion services, changes
in contraceptive practices, attitudinal changes concerning abortion
and/or carrying unplanned pregnancies to term, and the possibility
that the number of unintended pregnancies have decreased (4-6).

In other countries, the rate for legal abortions per 1,000
women of reproductive age ranged from greater than 100 in the
former Soviet Union to five in the Netherlands (7). The induced
abortion rate in the United States was higher than that reported by
Australia, Canada, and Western European countries, and lower than
that reported by China, Cuba, the Eastern European countries, and
the Newly Independent States of the Soviet Union (7). Abortion
rates for teenagers were higher in the United States than in most
Western European countries and some Eastern European countries (7).

The abortion ratio in 1991 varied substantially by age.
Although the ratio was highest for teenagers, the percentage of
legal abortions obtained by women less than 19 years of age has
decreased steadily since the mid-1980s -- from 26% in 1984 to 24%
in
1989 and to 21% in 1991 (2,8). Since 1980, the abortion ratio
declined for most age groups -- particularly for women less than 15
years of age and greater than or equal to 40 years of age. In 1991,
the abortion ratio for women 15-19 years of age was the lowest
ratio CDC had ever recorded for that age group. Increasing rates of
childbearing among teenage women and women greater than or equal to
35 years of age may have accounted for some of the decline in
abortion ratios for these age groups (3). The decline in the
abortion ratio for teenagers might also be associated with reduced
access to abortion services (5), recent changes in abortion laws
(e.g., parental consent or notification laws), and mandatory
waiting periods, all of which are likely to disproportionately
affect adolescents (9,10).

During 1991, the abortion ratio for black women was more than
twice that for white women, and the abortion rate for black women
was about three times that for white women. Race-specific
differences in abortion ratios and rates may reflect differences in
factors such as socioeconomic status, contraceptive use, and access
to family planning, contraceptive, and abortion services.

The abortion-to-live-birth ratio for Hispanic women during
1991 was slightly lower than that for non-Hispanic women. Other
published reports indicate that pregnant Hispanic women are less
likely than pregnant non-Hispanic women to obtain an abortion (11).
The abortion rate per 1,000 Hispanic women was higher than that for
non-Hispanic women. Other studies using previously published data
also reported higher abortion rates for Hispanic women than for
non-Hispanic women (11). For women in all age groups, fertility was
higher for Hispanic than for non-Hispanic women (3). However, in
1991, only 20 states, the District of Columbia, and New York City
reported the number and percentage of abortions by Hispanic
ethnicity; these geographic areas represent approximately 44% of
all Hispanic women of reproductive age in the United States (CDC,
unpublished data). Thus, the number, ratio, and rate of abortions
for Hispanic women in this surveillance summary might not be
representative of the overall Hispanic population in the United
States (i.e., these data might reflect utilization of abortion
services only in these states).

The percentage distribution of abortions by gestational age
was stable from 1980 through 1991 Table_1. In this and previous
reports, age was inversely associated with timing of abortion
(i.e., younger women were more likely to obtain an abortion later
in gestation than were older women) (2,12,13).

The percentage of women who were obtaining an abortion for the
first time decreased from 75% in 1974 to 55% in 1991 Table_12
(14). During this period, the percentage of women who previously
had had one induced abortion increased from 10% in 1974 to 25% in
1985 and to 27% in 1991 (8). The percentage who had had two
previous abortions increased from approximately 1% in 1974 to
approximately 10% in 1985; from 1985 through 1991, the percentage
remained at approximately 9%-10%. The percentage who had had three
or more abortions increased from 0.4% in 1974, to approximately 5%
in 1985; during 1990 and 1991, this percentage remained at 6%.
Because the proportion of all legal induced abortions that are
repeat procedures increases with the abortion rate, the proportion
of repeat procedures increased during the 1970s and early 1980s as
the abortion rate rose; since then, the abortion rate and the
proportion of repeat procedures have stabilized (13,15,16).

From 1972 to 1991, the percentage of abortions performed by
curettage (which includes D&E) increased from 89% to 99%
Table_1,
and the percentage of abortions performed by intrauterine
instillation and by hysterectomy and hysterotomy declined sharply
(from 10% to 1% and from 0.6% to 0.01%, respectively). From 1974
through 1991, the percentage of second-trimester abortions
performed by D&E increased from 31% to 92%; the percentage of
second-trimester abortions performed by intrauterine instillation
decreased from 57% to 5% (14). The increasing use of D&E might have
resulted from the lower risk for complications associated with the
procedure (17,18).

The numbers, ratios, and rates of abortion from this analysis
are conservative estimates because the number of legal abortions
reported to CDC for 1991 was probably lower than the number
actually performed. Totals provided by central health agencies are
often lower than those obtained by direct surveys of abortion
providers (19). For example, the total number of abortions reported
to CDC for 1991 was approximately 12% lower than that reported by
The Alan Guttmacher Institute, a private organization that directly
contacts abortion providers to obtain information on the number of
abortions performed (6).

Despite these limitations, findings from ongoing national
surveillance of legal induced abortion are used for several
purposes. First, data from abortion surveillance are used to
identify characteristics of women at high risk for unintended
pregnancy. Second, ongoing surveillance is essential to monitor
trends in the number, ratio, and rate of abortions in the United
States. Third, statistics on the number of pregnancies ending in
abortion are used in conjunction with birth statistics to estimate
pregnancy rates (e.g., pregnancy rates among teenagers) (20) and
other outcome rates (e.g., the rate of ectopic pregnancies per
1,000 pregnancies). Fourth, abortion and pregnancy rates can be
used to evaluate the effectiveness of family planning programs and
programs for preventing unintended pregnancy. Fifth, ongoing
surveillance also provides data for assessing changes in clinical
practice patterns related to abortion (e.g., longitudinal changes
in the types of procedures). Finally, abortion data are used as the
denominator in calculating abortion morbidity rates and
case-fatality rates.

Induced abortions are linked usually to unintended
pregnancies, which often occur despite use of contraception
(11,21,22). In the late 1980s, about 1.2 million live births
occurred for which the pregnancy was unintended (i.e., either
mistimed or unwanted at conception) (23). Improved contraceptive
practices, as well as access to and edu-cation regarding safe,
effective, and low-cost contraception and family planning services,
can help minimize abortion in the United States (24).

Not all states have acknowledged the need for state-based
abortion surveillance, and some states that have recognized the
need have been unable to gather such information. Some states
emphasize the prevention of unintended pregnancy, particularly
among teenagers. To help guide this effort, however, an ongoing,
accurate assessment of abortion is needed in all states to
determine the number and characteristics of women who obtain
abortions.

National Center for Health Statistics, Williams L, Pratt WF.
Wanted and unwanted childbearing in the United States 1973-88.
Hyattsville, MD: US Department of Health and Human Services, Public
Health Service, CDC, 1990;(189):1-7. (Advance data).

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